JP2513093B2 - X-ray fluorescence analyzer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises irradiating a sample with X-rays to excite the element contained in the sample and analyzing the wavelength of fluorescent X-rays emitted when the element returns to a stable state. The present invention relates to a fluorescent X-ray analysis device for identifying a substance and measuring its content.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a main part of a conventional fluorescent X-ray analyzer of this kind.

In the figure, 2 is an X-ray tube, 2a is its X-ray emission end face, 4 is an upper vacuum container, 6 is a lower vacuum container, 8 is a partition plate, and 10 is a shutter. Upper vacuum container 4
The lower vacuum container 6 and the lower vacuum container 6 are hermetically attached to the intermediate partition plate portion 8 via O-rings 12 and 14, respectively. The lower end of the X-ray tube 2 is inserted into the upper vacuum container 4 and attached in a sealed state via an O-ring 16.

The shutter 10 opens and closes the opening 8a of the intermediate partition plate 8 by a drive mechanism (not shown), and is kept airtight by the O-ring 18 in the closed state. The vacuum chamber 20 includes the lower end portion of the X-ray tube 2, the upper vacuum container 4, the intermediate partition plate portion 8 and the shutter 10 in the closed state.
Are formed. The upper vacuum container 4 is provided with an exhaust unit 22 for evacuating the vacuum chamber 20 and a spectroscopic detection unit 24 is attached.

Reference numeral 26 receives a sample holder 34, which will be described later, and a sample insertion port 6a formed in the lower vacuum container 6.
Is a pedestal / cover lid that fits and closes. The pedestal / cover lid 26 is fitted and closed in the sample insertion port 6a, so that the lower vacuum container 6 and the intermediate partition plate 8 are in a closed state. A preliminary exhaust chamber 28 is formed by the shutter 10 and the pedestal / cover 26. In order to enhance the airtightness of the pedestal / cover lid 26 with respect to the sample insertion port 6a, the sample insertion port 6a
Also, the pedestal / cover lid 26 is formed in a downwardly widened taper, and the O-ring 30 is attached to the taper surface of the sample insertion port 6a.

The lower vacuum container 6 is provided with an exhaust portion 32 for exhausting the preliminary exhaust chamber 28 to vacuum.

The sample holder 34 is for holding the sample m in an accurate positioning state, and is composed of a cylindrical portion 34a, a sample stopper 34b, a bottom plate 34c, a sample mounting plate 34d, a compression spring 34e and the like. . The sample m positioned and mounted on the sample mounting plate 34d has a compression spring 34 provided between the bottom plate 34c and the sample mounting plate 34d.
The upper surface thereof is brought into pressure contact with the sample stopper 34b by the urging force of e. A communication hole 34f communicating with the preliminary exhaust chamber 28 is formed in the cylindrical portion 34a.

The sample holder 34 includes a pedestal lid 26.
It is fitted in and held by and is moved up and down integrally with the pedestal / cover lid 26 by an elevating mechanism (not shown).

Next, the operation of the conventional X-ray fluorescence analyzer constructed as above will be described.

The sample holder 34 holding the sample m is fitted and held in the pedestal / cover lid 26, and the sample holder 34 and the cradle / cover lid 26 are integrally lifted by an elevator mechanism (not shown). At this stage, the shutter 10 is already in the closed posture, and the vacuum chamber 20 is kept in a high vacuum state by the vacuum exhaust from the exhaust unit 22. On the other hand, the preliminary exhaust chamber 28 has the same pressure as the outside air pressure.

The sample holder 34 is inserted into the preliminary evacuation chamber 28 through the sample insertion port 6a of the lower vacuum container 6, and the pedestal / cover lid 26 is closely fitted to the sample insertion port 6a and sealed by the O-ring 30. Close to the state. Then, the inside of the preliminary exhaust chamber 28 is evacuated by the exhaust unit 32. At this time, the inside of the sample holder 34 is also evacuated through the communication hole 34f.

The degree of vacuum in the preliminary evacuation chamber 28 is monitored, and when it is reduced to the same level as the vacuum chamber 20, the shutter 10 is opened by a drive mechanism (not shown). Since the inside and outside of the sample holder 34 are communicated with each other through the communication hole 34f, there is no pressure difference, and the upper surface of the sample m pressed by the sample stopper 34b by the compression spring 34e and the X-ray emission end surface 2a of the X-ray tube 2 are. Distance and parallelism are kept constant.

When the shutter 10 moves to the open end, X
X-rays are radiated from the X-ray emission end face 2a of the X-ray tube 2 toward the sample m, and the fluorescent X-rays emitted from the sample m are spectroscopically detected.
And spectrally analyze the wavelength and intensity patterns.

When this is completed, the shutter 10 is closed again to keep the vacuum chamber 20 in a high vacuum state, and then the pedestal / cover 26 together with the sample holder 34 is lowered by an elevating mechanism (not shown) to remove the sample holder 34. The sample is taken out from the preliminary exhaust chamber 28 through the sample insertion port 6a.

[0015]

However, the above-mentioned conventional fluorescent X-ray analyzer has the following problems.

Since the sample holder 34 is carried into the preliminary evacuation chamber 28 and the sample insertion port 6a is sealed by the pedestal / cover lid 26, the preliminary evacuation chamber 28 is evacuated. The volume of the sample holder 3 is 28.
It needs to be large enough to accommodate 4. Since the preliminary exhaust chamber 28 has such a large volume, it takes a considerably long time to evacuate the preliminary exhaust chamber 28, resulting in poor efficiency.

Depending on the sample m, the air may be replaced with an inert gas such as helium without evacuating the preliminary exhaust chamber 28. In this case, the inert gas introduction following the air purge is performed. Therefore, it takes extra time.

Further, a sample holder 34 is attached to the lid 26 which also serves as a pedestal.
The structure is such that the pedestal and lid 26 must be fitted tightly and closely to the sample insertion opening 6a of the lower vacuum container 6 and the O-ring 30. , The structure of these parts is complicated.

The present invention was devised in view of such circumstances, and an object thereof is to shorten the time required for vacuum exhaust or gas replacement and to simplify the structure.

[0020]

In a fluorescent X-ray analysis apparatus according to the present invention, a vacuum chamber facing the respective tip portions of an X-ray tube and a spectroscopic detection section is constructed so as to be openable and closable by a shutter, and a vacuum chamber is provided immediately below the shutter. Is provided with a flat plate-shaped main body bottom plate in a posture parallel to the shutter that secures a shutter opening / closing space having a width slightly larger than the thickness of the shutter, and exhausts the inside of the shutter opening / closing space facing the shutter opening / closing space. An opening is formed in the main body bottom plate at a position facing the X-ray tube, and the upper surface of the sample held by the sample holder in an upwardly biased state faces the opening. The upper end surface of the sample holder is configured to be capable of sealingly contacting the lower surface of the main body bottom plate, and the main body bottom plate,
A communication hole that communicates the shutter opening / closing space with the inside of the sample holder is formed.

[0021]

Operation: The sample holder is raised and its upper end surface is brought into contact with the bottom plate of the main body in a sealed state. At this time, the upper surface of the sample biased upward is in contact with the main body bottom plate. Further, the communication hole of the bottom plate of the main body communicates the inside of the sample holder with the shutter opening / closing space. Then, after the shutter opening / closing space and the inside of the sample holder are evacuated or replaced with gas by the exhaust unit, the shutter is opened and the sample is irradiated with X-rays from the X-ray tube through the opening in the bottom plate of the main body. The fluorescent X-rays are guided to the spectroscopic detector.

In this case, the objects of vacuum evacuation or gas replacement by the evacuation unit are only the shutter opening / closing space and the inside of the sample holder, not the large preliminary evacuation chamber as in the conventional example. In the sample holder, the upper end surface of the sample holder directly abuts the bottom plate of the main body to ensure the hermeticity by the sample holder itself, so that the preliminary exhaust chamber itself of the conventional example is not necessary.

The target of vacuum evacuation or gas replacement is not the preliminary evacuation chamber but only the shutter opening / closing space and the inside of the sample holder, and the shutter opening / closing space has a small capacity whose vertical width is slightly larger than the shutter thickness. Therefore, the volume as a whole is significantly reduced as compared with the conventional example having the preliminary exhaust chamber.

Further, since the preliminary exhaust chamber itself is omitted, the pedestal / cumulative lid in the conventional example is also unnecessary.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the X-ray fluorescence analyzer according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing a main part of the X-ray fluorescence analyzer of the embodiment, and FIG. 2 is an enlarged sectional view of the main part.

The upper vacuum vessel 4 into which the lower end of the X-ray tube 2 is inserted and which is hermetically attached via the O-ring 16 is attached to the intermediate partition plate portion 8 in the hermetically-sealed state via the O-ring 12. ing. A shutter 10 that opens and closes the opening 8 a of the middle partition plate portion 8 is arranged on the lower surface of the middle partition plate portion 8.

A shutter 10 is provided on the lateral side of the upper vacuum container 4.
Drive mechanism is arranged. That is, the motor 40,
Reduction gear case 42, drive shaft 44, coupling 46,
A passive shaft 48 is provided, and a shutter plate 50 holding the shutter 10 is attached to the lower end of the passive shaft 48.

In the closed state of the shutter 10 with respect to the opening 8a of the intermediate partition plate portion 8, the shutter 10 is brought into contact with the O-ring 18 fitted to the lower surface of the intermediate partition plate portion 8 to maintain airtightness. There is.

A vacuum chamber 20 is formed by the lower end of the X-ray tube 2, the upper vacuum container 4, the partition plate 8 and the shutter 10 in the closed state. The upper vacuum container 4 is provided with an exhaust unit 22 for evacuating the vacuum chamber 20 and a spectroscopic detection unit 24 is attached. The X-ray emission end face 2a of the X-ray tube 2 and the incident end face 24 of the spectroscopic detection unit 24.
a faces the inside of the vacuum chamber 20. X-ray emission end face 2a
And the opening 8a are coaxial.

Shutter 10 and shutter plate 50
A bottom plate 54 of a flat plate shape for ensuring a shutter opening / closing space 52 having a width slightly larger than the thickness of the shutter 10 is arranged immediately below the main plate bottom plate 54 with respect to the middle partition plate part 8. It is attached in a sealed state via an O-ring 56. The main body bottom plate 54 is parallel to the shutter 10 and the shutter plate 50.

As is clear from the comparison between FIG. 1 and FIG.
The shutter opening / closing space 52 formed between the middle partition plate portion 8 and the main body bottom plate 54 has a volume sufficiently smaller than that of the preliminary exhaust chamber 28 of the conventional example. Middle partition plate 8
Is provided with an exhaust unit 58 for evacuating the shutter opening / closing space 52.

An opening 54a is formed coaxially in the bottom plate 54 of the main body so as to face the X-ray emission end face 2a of the X-ray tube 2. The upper surface of the sample m comes into contact with the lower surface of the main body bottom plate 54 in the vicinity of the periphery of the opening 54a.

As shown in FIG. 2, the sample holder 60 for holding the sample m in an accurate positioning state is composed of a cylinder portion 60a, a flange portion 60b, a bottom plate portion 60c, a sample mounting plate 60d, a compression spring 60e and the like. ing. Bottom plate 60
c is internally fitted to the tubular portion 60a and is fitted to the bottom plate portion 60c.
The ring 60f maintains airtightness with the tubular portion 60a. The bottom plate portion 60c is fixed by a stopper screw 60g screwed into the tubular portion 60a. The sample mounting plate 60d is
A compression spring 60e interposed between the bottom plate portion 60c and the sample mounting plate 60d urges it upward, and the flange portion 60b receives the compression spring 60e (indicated by a chain double-dashed line in FIG. 2).

When the sample holder 60 is lifted from the position indicated by the chain double-dashed line in FIG. 2 to the position indicated by the solid line by a lifting mechanism (not shown), first, the outer peripheral portion of the upper surface of the sample m is opened 54a.
In contact with the lower surface of the bottom plate 54 of the main body in the periphery of the, the sample mounting plate 60d is lowered relative to the tubular portion 60a while contracting the compression spring 60e.

By further raising the sample holder 60, the flange portion 60b abuts on the lower surface of the main body bottom plate 54 at the outer peripheral position of the sample abutting portion. An O-ring 62 is fitted to the main body bottom plate 54 at the abutting portion of the flange portion 60b, and the airtightness between the sample holder 60 and the main body bottom plate 54 is maintained by the abutment.

In the annular region between the abutting portion of the sample m and the abutting portion of the flange portion 60b on the main body bottom plate 54, the main body bottom plate 54 has a communication hole for communicating the shutter opening / closing space 52 and the inside of the sample holder 60. A plurality of 64 are formed at appropriate intervals in the circumferential direction.

Here, comparing the present embodiment with the conventional example, in the present embodiment, the lower vacuum container 6, the pedestal / cover 26 and the large-capacity preliminary exhaust chamber 2 in the conventional example are shown.
8 does not exist.

Next, the operation of the X-ray fluorescence analyzer of the present embodiment constructed as described above will be described.

As shown by the alternate long and two short dashes line in FIG. 2, first, the sample m is placed and fitted to the sample placing plate 60d of the sample holder 60 in a positioned state. At this time, the sample mounting plate 60d is biased upward by the compression spring 60e and is received by the flange portion 60b. Further, the shutter 10 is in the closed posture, and the vacuum chamber 20 maintains a high vacuum.

When the sample holder 60 is raised together with the sample m by an elevating mechanism (not shown), first, the upper surface of the sample m abuts the main body bottom plate 54 around the opening 54a,
Vertical position regulation is performed.

When the sample holder 60 is subsequently raised, the position of the sample m is regulated, and as shown by the solid line in FIG. 2, the flange portion 60b is in close contact with the O-ring 62 at the outer peripheral position of the communication hole 64. It contacts the bottom plate 54 of the main body. As a result, the sample holder 60 is brought into contact with the bottom plate 54 of the main body in a sealed state. Further, the inside of the sample holder 60 is in communication with the shutter opening / closing space 52 by the plurality of communication holes 64 in the circumferential direction.

A shutter opening / closing space 52 is provided through an exhaust unit 58.
Further, the inside of the sample holder 60 communicating with this via the communication hole 64 is evacuated (it may be replaced with an inert gas after gas purging depending on the type of the sample m).

When the vacuum exhaust is completed, the motor 40 is driven to slide the shutter 10 through the shutter plate 50 to open the opening 8a. As a result, the shutter opening / closing space 52 is in a high vacuum state, which is about the same as the vacuum chamber 20. The X-ray emitting end surface 2a of the X-ray tube 2 directly faces the upper surface of the sample m.

Since the upper surface of the sample m is biased upward by the compression spring 60e and pressed by the lower surface of the bottom plate 54 of the main body to regulate its position, the distance and parallelism between the X-ray emission end surface 2a and the upper surface of the sample m are small. It is always kept constant.

After opening the shutter 10, the X-ray of the X-ray tube 2 is changed.
Sample m from the line emission end face 2a through the openings 8a and 54a
And irradiate X-rays toward the optical axis to guide the fluorescent X-rays emitted from the sample m from the incident end face 24a to the spectroscopic detection unit 24, where they are dispersed.
Analyze wavelength and intensity patterns.

When this analysis is completed, the shutter 10 is closed and the vacuum chamber 20 is kept in a high vacuum state, and then the exhaust unit 58.
The vacuum of the shutter opening / closing space 52 is released via the
At the same time, the sample holder 60 is lowered by an elevator mechanism (not shown).

In the above case, the target of vacuum exhaust or gas replacement by the exhaust unit 58 is the shutter opening / closing space 52.
Since only the inside of the sample holder 60 and the shutter opening / closing space 52 have a sufficiently smaller volume than the preliminary exhaust chamber 28 of the conventional example, the time required for exhaust or gas replacement can be greatly shortened. Further, since the pedestal and lid 26 as in the conventional example is not required, the structure is simple.

Although the upper surface of the sample is brought into contact with the lower surface of the main body bottom plate 54 in the above embodiment, the conventional sample holder shown in FIG. 3 is used and the sample holder is formed on the main body bottom plate 54. A communication hole may be formed at a position corresponding to the formed communication hole 64. Further, the O-ring 62 for sealing the flange portion 60b of the sample holder 60 and the main body bottom plate 54 is provided on the main body bottom plate 54 side, but the present invention is not limited to this, and conversely it is O The ring may be provided on the flange portion 60b. However, it is advantageous to provide the O-ring on the bottom plate 54 side of the main body because the O-ring can be shared by a plurality of sample holders 60, which is advantageous in cost reduction.

[0050]

According to the present invention, since the sample holder itself, which is brought into direct contact with the main body bottom plate, ensures the hermeticity, the preliminary exhaust chamber itself of the conventional example can be omitted, and the main body bottom plate is used. Since the shutter opening / closing space to be used is of a small capacity, which is only slightly larger than the shutter thickness, the volume of the shutter opening / closing space and the sample holder inside, which is the target of vacuum evacuation or gas replacement, is significantly smaller than the conventional example. The time required for evacuation or gas replacement can be significantly shortened and efficiency can be improved. Further, by omitting the preliminary exhaust chamber, the conventional pedestal / cumulative lid is not required, and the structure can be simplified.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an X-ray fluorescence analyzer according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a cross-sectional view showing a main part of a conventional fluorescent X-ray analyzer.

[Explanation of Codes] 2 X-ray tube 54 Main body bottom plate 2a X-ray emission end face 54a Opening 4 Upper vacuum container 58 Exhaust part 8 Partition plate part 60 Sample holder 8a Opening part 60a Cylindrical part 10 Shutter 60b Flange part 20 Vacuum chamber 60c Bottom plate part 22 Exhaust part 60d Sample mounting plate 24 Spectral detection part 60e Compression spring 24a Incident end face 60f O-ring 50 Shutter plate 62 O-ring 52 Shutter opening / closing space 64 Communication hole

Claims (1)

(57) [Claims] 1. An X-ray tube and a vacuum chamber facing each tip of the spectroscopic detection unit are configured to be opened and closed by a shutter, and a shutter opening / closing space having a vertical width slightly larger than the thickness of the shutter is provided immediately below the shutter. Is provided with a flat plate-shaped main body bottom plate in a posture parallel to the shutter, and an exhaust portion for exhausting the shutter open / close space facing the shutter open / close space is provided. An opening is formed at a position facing each other, the upper surface of the sample held by the sample holder in an upwardly biased state faces the opening, and the upper end surface of the sample holder is sealed to the lower surface of the main body bottom plate. The X-ray fluorescence analyzer, characterized in that the bottom plate of the main body is formed with a communication hole that communicates the shutter opening / closing space with the inside of the sample holder.